Back to EveryPatent.com
United States Patent |
5,655,752
|
De Villepoix
,   et al.
|
August 12, 1997
|
System with imperviousness joint compressed between two non-parallel
bearings
Abstract
Imperviousness system composed of a metallic toric joint (9) compressed
between two bearings (27, 28) which together form an acute angle (.alpha.)
so as to produce a sliding and polishing of the skin of the joint and
reduce the local levellings which would compromise the imperviousness
capacity of the joint on each closing operation.
Inventors:
|
De Villepoix; Raymond (Donzere, FR);
Rouaud; Christian (Bourg Saint-Andeol, FR)
|
Assignee:
|
Commissariat a l'Energie Atomique (FR)
|
Appl. No.:
|
478989 |
Filed:
|
June 7, 1995 |
Foreign Application Priority Data
Current U.S. Class: |
251/359; 251/174; 251/357; 251/358 |
Intern'l Class: |
F16K 001/22 |
Field of Search: |
251/359,357,358,174,176
|
References Cited
U.S. Patent Documents
1427680 | Aug., 1922 | English.
| |
3077332 | Feb., 1963 | Burtis | 251/174.
|
3199833 | Aug., 1965 | Skinner, Jr. | 251/176.
|
4258901 | Mar., 1981 | Zinnai et al. | 251/174.
|
4296915 | Oct., 1981 | Baumann | 251/174.
|
4658847 | Apr., 1987 | McCrone | 251/174.
|
5178364 | Jan., 1993 | Garrigues et al. | 251/174.
|
5249774 | Oct., 1993 | Mazel et al. | 251/174.
|
Foreign Patent Documents |
2253170 | Jun., 1975 | FR.
| |
1325997 | Aug., 1973 | GB.
| |
84/00058 | Jan., 1984 | WO.
| |
Primary Examiner: Chambers; A. Michael
Attorney, Agent or Firm: Londa and Traub LLP
Claims
What is claimed is:
1. Imperviousness system comprising a valve body portion having a
substantially flat first bearing surface, a clack valve having a second
bearing surface, and a sealing element disposed between the first and
second bearing surfaces, wherein the sealing element is toric, elastic and
has a metallic outer casing, and the first and second bearings form
therebetween an acute angle of less than or equal to 45.degree..
2. System according to claim 1 wherein the value of the acute angle is
directly linked to the nature of the gasket and the value of the clamping
force of the clack valve.
3. System according to claim 1, wherein the joint includes an open casing
extending into a tongue resting on one of the bearings.
4. System according to claim 3, wherein the tongue covers a throat hollowed
in said one of the bearings on which it rests, the throat containing a
static imperviousness joint, the system further comprising a flange
compressing the tongue on the static joint.
5. System according to claim 4, wherein the static joint includes a casing
extending the tongue.
6. System according to claim 3, wherein the tongue is extended by an open
casing of a static imperviousness joint compressed on said one of the
bearings on which the tongue rests via a flange.
7. System according to claim 3, wherein said one of the bearings on which
the tongue rests is flat.
8. System according to claim 1, wherein the acute angle opens outside the
joint.
9. System according to claim 1, wherein the acute angle opens towards the
inside of the joint.
10. System according to claim 1, wherein the metallic outer casing is
composed of aluminum and the angle is between about 10.degree. to
15.degree..
11. System according to claim 1, wherein the metallic outer casing is
composed of silver and the angle is between about 20.degree. to
30.degree..
12. System according to claim 1, wherein the metallic outer casing is
composed of copper and the angle is between about 25.degree. to
35.degree..
13. System according to claim 1, wherein the metallic outer casing is
composed of nickel and the angle is between about 30.degree. to
40.degree..
14. System according to claim 1, wherein the metallic outer casing is
composed of stainless steel and the angle is between about 35.degree. to
45.degree..
15. Imperviousness system comprising a valve body portion having a
substantially flat first bearing surface, a clack valve having a second
bearing surface, and a sealing element disposed between the first and
second bearing surfaces, wherein the sealing element is toric, elastic and
has a metallic outer casing, and the first and second bearings form
therebetween an acute angle, the sealing element comprising a tongue
extending from the outer casing, one of said bearing surfaces comprising a
throat formed as a recess therein, wherein the tongue is flat along a
contact surface thereof which faces the throat, such that the contact
surface does not enter the area of the throat.
Description
FIELD OF THE INVENTION
The invention concerns an imperviousness system including in particular a
joint compressed between non-parallel bearings.
BACKGROUND OF THE INVENTION
To date, there are many devices able to periodically re-establish
imperviousness between two elements via the repetition of a relative
movement of two mechanical pieces which clamp a gasket and in particular
slide valves, clack valves, cocks and inspection doors with periodical
opening and closing. In some of these devices, the gasket is metallic and
elastic and is compressed between bearings made of an identical or
different metal. Certain criteria, such as fire-resistance, a high working
temperature and the need to obtain a high vacuum, may in fact impose that
other materials be excluded.
SUMMARY OF THE INVENTION
A conventional cock system is described and shown on FIG. 1. This figure
shows a cock body 1 associated with a control member 2 engaged in a sleeve
3 of the body 1 and which in particular includes an operating rod 4
controlled by an external flywheel 5. The operating rod 4 is ended at the
other end by a clack valve 6 orientated towards a seat or valve body
portion 7 and equipped with a gasket or plubing element 9, also known as a
clack valve joint.
The seat 7 belonging to the body 12 is situated inside the latter at the
junction point of two pipe segments 10 and 11 which each end at flanges 12
and 13 to the extremities of the body 1 to which pipework may be
connected.
A mechanical device, such as a nut/screw link between the operating rod 4
and the flywheel 5 and a wedge between the operating rod 4 and the body 1
makes it possible to convert the rotation of the flywheel 5 into an axial
movement of the operating rod 4 and of the clack valve 6 which may move
forwards towards the seat 7 until the joint 9 is compressed between one
bearing 14 of the seat 7 and one bearing 15 of the clack valve 6.
Communication between the two elements formed by the pipe segments 10 and
11 is then interrupted but may be re-established via an inverse movement
of the clack valve 6. Finally, stacked elastic washers 8 disposed between
the body 1 and a shoulder of the flywheel 5 push the latter back towards
the seat and generally keep it in a uniform position.
Amongst existing joints able to be compressed between two metallic
elements, toric-shaped elastic metallic gaskets are retained for the
present invention, although this particular selection is given solely by
way of non-restrictive example, said gaskets including a metallic core
constituted by a helical spring with contiguous spires enclosing itself to
form a circle, and at least one metallic outer casing in which the
metallic core is embedded and having a C-shaped or ring-shaped section.
When this type of joint is compressed between two flanges or bearings, it
can be identified by virtue of its force characteristic as a function of
crushing, an example of this being given in FIG. 2. Compression starts
with a fully rectilinear curved portion 20, namely that crushing is
proportional to the force and continues by a portion expressing a least
resistance of the joint, namely an increase of a weaker force produces
more significant crushing. In practice, the compression of the joint 9
stops according to the resistance provided by the elastic washers 8 in the
operating rod 4/flywheel 5 system: in turn, they also buckle and are
crushed in undergoing a specific force. The decompression curve 22 of the
joint 9 is produced with hysteresis allowing a significant residual
crushing to exist after removal of the joint 9 from the bearing of the
seat 14. The next compression of the joint 9 shall be effected along a
curve 23 more or less parallel to the first compression curve 20 and 21,
but it shall be observed that the force Y2 required to re-establish
imperviousness is much greater than the force Y1 which would suffice on
the first occasion. It can be seen that the same would apply for each
subsequent use, which means that a metallic toric joint as defined above
cannot be used for a long period of time so as to renew imperviousness
between the two bearings 14 and 15 as the force required to re-establish
imperviousness would exceed the force able to be applied at the end of a
few manoeuvres.
It is to be noted that the evolution of the force for creating
imperviousness Y follows a linear progression 24 with respect to the
logarithm of the number of manoeuvres of the clack valve 6 (FIG. 4) for
the joint 9 clamped between the two parallel bearings 14 and 15 (FIG. 3).
To find a way out to this persistent increase of the imperviousness force
threshold on each new usage, the present invention proposes to change the
respective disposition of the bearings of the seat 7 and the clack valve
6. More specifically, they shall collectively form an acute angle.
BRIEF DESCRIPTION OF THE DRAWINGS
There now follows a more detailed description of the principle and
embodiments of the present invention accompanied by the following figures
given by way of non-restrictive illustration:
FIGS. 1 and 2, already described, illustrate an imperviousness system and
the characteristic crushing curve of a joint,
FIG. 3, already described, represents the basic elements of conventional
imperviousness systems,
FIG. 4, already described, illustrates the degradation of the aptitude of
conventional imperviousness systems when carrying out their particular
task,
FIG. 5 shows in correspondence with FIG. 3 the basic elements of the
imperviousness systems in accordance with the invention,
in correspondence with FIG. 4, FIG. 6 illustrates the preservation of the
aptitude of the imperviousness systems in accordance with the invention
when fulfilling their particular task,
and FIGS. 7 to 14 illustrate eight embodiments of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
First of all (FIG. 5), reference is made to the same joint 9 compressed
between a fixed flat face 27 and a mobile conical face 28 forming between
then an acute angle .alpha.. This characteristic makes it possible to
avoid the joint 9 being hammered on each compression accompanied by a
local plastic crushing levelling the hammered facets and unceasingly
widening the contact zone of the joint together with the imperviousness
bearings on account of the opening and closings of the clack valve 6. In
fact, the initial contact point A of the conical bearing 28 with the
represented section of the joint 9 is not diametrically opposite the
contact point C with the flat face 27 and shall move at A' parallel to the
displacement direction of the conical bearing 28 at the time it moves via
a height AA' with as a corollary a crushing of the adjacent portion of the
joint 9 which means that the initial contact point A shall move towards
the point B a short distance away from the new contact point A' As a
result, the joint 9 and the conical bearing 28 slide onto each other by a
length BA' equal to AB.multidot.tg.alpha., or AA'.multidot.sin .alpha. and
thus fully determined.
This sliding produces modifications on a microgeometrical scale of the
surface of the joint which can be compared with a polishing which is
maintained with the repetition of clamping and unclampings. It is to be
noted that in these circumstances, in accordance with the curve 29 of FIG.
6, the force required to establish imperviousness stabilises between ten
and one hundred manoeuvres. It ought to be mentioned that the surface
roughness of the conical imperviousness face 28 needs to be able to favor
polishing, namely that it needs to be neither too fine nor thick and can
be situated around 0.5 to 1 .mu.m of height of the relief unevenness. The
joint 9 also needs to be sufficiently smooth and exhibit a surface state
free from defects, such as those which often appear on laminated plates
used in the production of joints with thin casings. This result may be
easily obtained by relatively current production methods, such as flow
turning or circular burnishing carried out at the end of production, or
even by a surface treatment, such as a plasma electrochemical depositing
or vapor phase physical depositing. This overall behaviour is valid,
irrespective of the nature of the metal forming the outer skin of the
metallic joint and in particular metals such as aluminium, silver, copper,
nickel or stainless steel. In order to favor and maintain polishing, it
shall suffice to correctly select the clamping force of the joint which
shall remain constant, and in particular the angle .alpha. so as to take
account of the crushing of the joint 9 on each manoeuvre which depends
directly on the ductibility of this metal.
For less ductile metals, the value AB is smaller with a constant force
which makes it necessary to increase the angle .alpha. so as to
re-establish the sliding length BA'.
Table I gives experimental results carried out over one thousand manoeuvres
for imperviousness levels measured with helium of between 10.sup.-10 to
10.sup.-8 Pa.m.sup.3 /s/m.
TABLE I
______________________________________
CONSTANT FORCE Y
Type of joint covering
(daN/cm of length of joint)
.alpha.
______________________________________
Aluminum 80 to 120 10 to 15.degree.
Silver 80 to 120 20 to 30.degree.
Copper 90 to 130 25 to 35.degree.
Nickel 100 to 140 30 to 40.degree.
Stainless steel
120 to 150 35 to 45.degree.
______________________________________
This polishing effect is not produced with the flat compression bearing 27
of the joint 9. Indeed, the joint 9 may be disposed between two conical
bearings so as to ensure complete imperviousness by the joint 9 alone, but
it is not always possible to choose the shape of the bearings and the
mounting of the joint 9 on a flat bearing, such as 27, is more stable. The
action of the joint 9 is then completed by a static joint which may be
partially formed by an elongation of the outer casing of the toric joint
in the form of a plain tongue. The main joint or sliding joint shall
therefore be compressed between the clamping bearings of the seat and
shall ensure imperviousness against the conical bearing, whereas the
gasket shall be compressed between the flat bearing and a clamping element
connected to the element bearing the flat bearing and shall ensure
imperviousness against the flat bearing.
This particular situation is advantageous in that it embodies a strict
association between the two joints which is shown on the other figures to
be described as follows.
FIG. 7 shows a joint 9a compressed between the bearings 27 and 28 and, as
said earlier, is composed of an internal core 30 formed of the spires of a
spring and a casing 31 open towards the outside which surrounds the core
30 via the top (on the side of the conical bearing 28), via the internal
face and via the bottom (on the side of the flat bearing 27) and which is
extended outwardly into a flat tongue 27 and which receives a second joint
34, possibly metallic and being of the same type or different.
A flange 35, solidly fixed by screws 36 to the seat 37, presses the tongue
32 against the flat bearing 27 (which belongs to the seat 37) and
compresses the second joint 34 in its throat 33 by means of the tongue 32.
The second joint 34 ensures the imperviousness of the system between the
tongue 32 and the flat bearing 27.
FIG. 8 shows a view of an almost similar embodiment, except the main joint
9b has a casing 41 opening inwardly and whose tongue 42 extends also
towards the inside of the space surrounded by the joint 9b in the same way
as the clamping flange 45 of the second joint 44 which surrounds the joint
9b. All the other comments of FIG. 7 apply to the latter. In particular,
the main joint 9b ensures imperviousness against the conical bearing 28
and the second joint 44 ensures imperviousness against the flat bearing
27.
Other embodiments use a single joint to ensure imperviousness on the two
bearings 27 and 28. Thus, the joint 9c of FIG. 9 includes a casing 51
composed of a tongue wound at its two opposing ends : one of the ends 53
surrounds a core 54 compressed between the bearings 27 and 28 and the
other end 55 bears a core 56 compressed at the bottom of a throat by a
flange, as for FIG. 7. The cores 54 and 56 thus correspond to those of the
main joint 9a or 9b and respectively to the second joint 34 or 44.
An almost similar embodiment is shown on FIG. 10 where the joint 9d has a
casing 57 without the tongue 52, that is where the bent back ends 53 and
55 are contiguous or almost meet.
FIG. 11 describes a joint 9e which resembles the joint 9c but with a
difference in that the ends 53 and in this instance 58 of the casing 59
also comprise the tongue 52 and are bent back in the same direction which
avoids having to hollow a throat in the flat bearing 27. The clamping
flange 60 bears a throat 61 for receiving the portion of the joint 9e
including the end 58 and which ensures imperviousness against the flat
bearing 27.
In all the preceding embodiments, the seat of the system has the flat
bearing 27 and the joint rests on this bearing. Now, the roles of the seat
and the clack valve may be inverted. This type of embodiment is shown on
FIG. 12 where a joint 9f with a shape similar to the joint 9c is disposed
on a clack valve 65 in a recess 66 provided with a central reinforcement
67. The bottom of the recess 66 forms a flat bearing for the joint 9f and
the conical bearing 69 is situated on the seat 70. A portion 721 of the
joint 9f (composed as elsewhere of a spring with contiguous spires
surrounded by a metallic casing) is compressed between the conical bearing
69 and the bottom of the recess 66, an opposing portion 72 (composed like
the preceding one) is compressed in the central reinforcement 67 by a
pressure screw 68, and an intermediate portion 73 composed of a flat
tongue portion of the metallic casing rests in the recess 66. The portions
71 and 72 thus ensure imperviousness against the conical bearing 69 and
the surface of the central reinforcement 67 between which they
respectively extend.
It is also possible that the angle .alpha. is not orientated so as to open
outside the joint 9 as in the preceding figures, but rather inwardly. This
embodiment is shown on FIG. 13 where the conical bearing 28' is therefore
orientated towards the inside of the joint 9a instead of being towards the
outside of the latter. This embodiment is identical to that of FIG. 7 as
regards all of its other aspects and functions in the same way. Finally,
the conception of FIG. 14 combines some of the preceding embodiments in
that it includes a joint 9g similar via its shape to the joint 9e but is
disposed differently on a clack valve, that is the static joint is
surrounded by the sliding joint and screwed down by a screw 75 fixed to
the clack valve 74 and the seat 76 has a conical bearing 69' orientated
towards the inside of the joint 9g.
One can easily see from this example that other modes are available for
combining the elements of the preceding figures.
Top